Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
  • A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
  • A61M5/1452—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons
  • A61M5/1454—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons spring-actuated, e.g. by a clockwork
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/33—Controlling, regulating or measuring
  • A61M2205/332—Force measuring means
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/82—Internal energy supply devices
  • A61M2205/8206—Internal energy supply devices battery-operated
  • A61M2205/8212—Internal energy supply devices battery-operated with means or measures taken for minimising energy consumption
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M39/00—Tubes, tube connectors, tube couplings, valves, access sites or the like, specially adapted for medical use
  • A61M39/22—Valves or arrangement of valves
  • A61M39/26—Valves closing automatically on disconnecting the line and opening on reconnection thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
  • A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
  • A61M5/1452—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons
  • A61M5/14566—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of pistons with a replaceable reservoir for receiving a piston rod of the pump
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
  • A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
  • A61M5/148—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons flexible, e.g. independent bags
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
  • A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
  • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
  • B05C17/01—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes with manually mechanically or electrically actuated piston or the like
  • B05C17/0136—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes with manually mechanically or electrically actuated piston or the like comprising an energy storing element, e.g. a spring, for exerting, e.g. when released, pressure on the material

Definitions

• the present invention relates to an infusion pump for administering controlled doses of a fluid, notably to an ambulatory infusion pump for administering fluid medicament to a patient.
• medicaments such as insulin for diabetics are more effective when administered in this manner, and particularly if the dosage can be adjusted automatically in response to changes in blood glucose levels.
• An ambulatory infusion pump is worn by a patient and can provide for such an improved dosing regime.
• WO 2004/024218 describes an infusion pump comprising a reservoir for storing a liquid agent, and a drive mechanism for propelling a piston towards an outlet from the reservoir in order to discharge the agent.
• the drive mechanism permanently forces the piston forwards, and a locking mechanism is provided for permanent locking of progress of the piston.
• the locking mechanism is released by operation of an escapement mechanism under electronic control for discharge of the agent.
• an infusion pump for administering controlled doses of a fluid
• the pump comprising: a receptacle for storing the fluid, the receptacle having an outlet for dispensing the fluid; a plunger; a propulsion mechanism which urges the plunger in a direction to pressurise the fluid and dispense it through the outlet; and a retaining member which acts on the plunger to control or prevent travel of the plunger; characterised in that the retaining member is operably connected to a stepper motor via a worm and worm-wheel drive.
• the worm-wheel drive of the present invention does not have a set stroke but instead can be used to accurately control, and change as required, the rate at which the retaining member extends from the wheel, thereby directly effecting the rate at which fluid is expelled from the syringe.
• the plunger pressurises the fluid by means of a piston which is located in the receptacle in contact, directly or indirectly, with the fluid.
• the plunger may itself comprise a piston, or alternatively, the piston may be secured to the plunger, for example, directly by means of an interference fit.
• an infusion pump for administering controlled doses of a fluid
• the pump comprising: a receptacle for storing the fluid, the receptacle having an outlet for dispensing the fluid; a piston in the receptacle; a propulsion mechanism which urges the piston towards the outlet to dispense the fluid; and a retaining member which acts on the piston to control or prevent travel of the piston towards the outlet; characterised in that the retaining member is operably connected to a stepper motor via a worm and worm-wheel drive.
• the angle of mating gear teeth of the worm and worm- wheel drive is preferably changed as compared to a normal worm and worm-wheel drive in which rotation of the worm would cause the wheel to turn whereas applying a torque to the wheel would normally fail to turn the worm.
• the gear set is normally incapable of being back-driven.
• the angle of the teeth is preferably chosen to provide a gear mechanism such that the gearbox is only just not capable of being back-driven by the torque applied to the wheel axle via the retaining means ("backdrive balance"). In this way, a very small torque applied to the worm, via the motor, will advantageously allow the wheel to rotate.
• This invention is particularly beneficial for an ambulatory infusion pump because it can reduce the size and weight of the pump, making it easier for the patient to wear. Also, the motor need use only a very small current, thereby providing for extended battery life and allowing the device to be worn for longer periods between recharging or replacing batteries.
• the propulsion mechanism which urges the plunger or piston towards the receptacle outlet may comprise a compression spring.
• the propulsion mechanism may comprise means such as a pressurised gas to urge the plunger/piston forwards.
• the receptacle is typically tubular, such as in the form of a syringe.
• the receptacle of the pump may comprise a collapsible container, such as an Intravenous (IV) bag with flexible walls or it may have a concertina-like structure.
• the plunger or piston pressurises the fluid by acting directly on a flexible wall of the container.
• the collapsible container is provided within the receptacle because this helps protect and position it, and define an external shape.
• the collapsible container is itself the receptacle for the fluid, and in such a case the receptacle is defined by the walls of the collapsible container.
• the pump may include external housing in which the receptacle is retained.
• the retaining member may comprise any suitable means for operably attaching the plunger to the motor via the worm drive, for example a cord, chain or cable.
• the retaining member may be wound around the axle of the worm-wheel, which functions as a capstan or winch. Accordingly, from another aspect, the invention provides a spring-driven infusion pump in which the release of the spring is controlled by a capstan or winch.
• the pump may further include a force detector for providing important information about the state of the pump, for example, whether the retaining member has broken or if there is an occlusion in the system.
• the force detector is located on an axle of the worm-wheel.
• the pump may include an electronic controller.
• the force detector may provide information specifically about the state of the retaining member (tight or slack) to an electronic controller.
• the pump may therefore be automated using the force detector and the electronic controller. For example, when the controller receives information from the detector that the retaining member is slack, the controller activates the stepper motor to take up the slack. Ideally, before the pump is used, the retaining member is fully wound and the stepper motor is stopped.
• the pump may include one or more sensors for providing feedback to the electronic controller, for example, for sensing (measuring) the force on the wheel axle, and/or for measuring the retaining member and/or the position of the plunger or piston.
• the electronic controller may include a boost function for inducing a rapid increase in the rate of expulsion of fluid.
• the controller may also limit the duration of any boost in rate according to clinical necessity.
• the controller may permit the user to press a button to cause a rapid short-term increase release of an analgesic if this does not cause the dose to exceed a harmful limit.
• the number and duration of such increased doses may be measured and limited by the controller to prevent a user overdosing.
• the flow rate of the fluid to the patient may be modified against a time base or modified by other influences such as user input (for example, to enable PCA - Patient Controlled Analgesia) or external equipment, which monitors the patient's vital signs.
• Electronically controlling the pump has other advantages such as providing dosing programs to predetermine the rate the fluid is dispensed from the receptacle for a specific duration.
• the outlet of the receptacle is provided with a screw thread for fitting into a cap having a mating-screw thread.
• the outlet is further provided with a valve member which will only permit fluid flow when it is inwardly displaced, for example, a luer- activated valve.
• the pump according to the invention is preferably provided with a brake mechanism to slow or stop the plunger from moving uncontrollably, for example, in the event the retaining member breaks.
• the plunger (or piston) may comprise a brake member in the form of a cruciform spring.
• the cruciform spring adopts a retracted configuration in which it does not engage with a wall of the receptacle.
• the plunger/piston is free to travel within the receptacle when the retaining means permits the propulsion mechanism to move the plunger.
• the cruciform spring adopts a substantially planar configuration and engages with the wall of the receptacle.
• the engagement between the cruciform spring and the wall induces a braking effect which stops or hinders the movement of the piston.
• the Applicant envisages that other braking mechanisms may be provided; for example the plunger may be caused to tilt if the retaining member breaks, causing jamming between the plunger or the piston and the receptacle wall.
• the brake mechanism is self-activating. More preferably, the greater the force urging the plunger to pressurise the liquid, the greater that force urges the brake to be deployed.
• an infusion pump for administering controlled doses of a fluid
• the pump comprising: a receptacle for storing the fluid, the receptacle having an outlet for dispensing the fluid; a plunger in the receptacle; a propulsion mechanism which urges the plunger towards the outlet to dispense the fluid; and a retaining member, optionally under electronic control, which acts on the plunger to control or prevent travel of the plunger towards the outlet; characterised in that the plunger includes a brake member which is adjustable between an active position in which it prevents or inhibits relative movement between the plunger and the outlet, and a passive position in which it does not prevent or inhibit movement; wherein the brake member is held in the passive position by the retaining member in normal operation but is released to adopt the active position if the retaining member fails.
• a further aspect of the invention therefore embraces a drive mechanism for an infusion pump for administering controlled doses of a fluid, the drive mechanism comprising: a plunger; a propulsion mechanism which urges the plunger in a predetermined direction; and a retaining member which acts on the plunger to control or prevent travel of the plunger; characterised in that the retaining member is operably connected to a stepper motor via a worm and worm-wheel drive.
• Figure 1 is a part sectional view of a first embodiment of an infusion pump in accordance with an aspect of the invention
• Figure 2 is a sectional view of another embodiment of an infusion pump in accordance with an aspect of the invention.
• Figure 3 is a sectional view along the line A-A of Figure 2;
• Figure 4 is a part sectional view of a further embodiment of an infusion pump in accordance with an aspect of the invention.
• Figures 5a, 5b and 5c each show a sectional view through of part of a device in accordance with a further aspect of the invention.
• the infusion pump shown in Figure 1 comprises a housing 10 in which is mounted a receptacle 2, in this example a syringe, for storing a liquid infusate 6.
• the syringe 2 has an outlet nozzle 8 for dispensing the liquid 6.
• a propulsion mechanism in this example a compression spring 14, acts on a plunger 12 to urge a piston 4 towards the outlet nozzle 8 to dispense the liquid 6.
• One end of the spring 14 is fixed to the housing 10, and the other end is fixed to the plunger 12. Unless restrained, the force of the spring 14 will drive the piston 4 all the way down the syringe 2 until it fully expels the liquid 6 and abuts the exit nozzle 8.
• a retaining member 16 in this example a cord or cable, for example having a spool diameter of approximately 8mm.
• the cord 16 is wound around an axle 20 of a worm-wheel 18 mounted to the housing 10 by a bracket 28, the axle 20 functioning as a capstan.
• the worm-wheel is turned by a worm 22 powered by a stepper motor 24.
• the motive force needed to infuse liquid infusate 6 into a patient is supplied by the operator (patient, clinician, doctor, carer, etc) compressing the spring 14 by loading a filled syringe 2 into the housing 10.
• the filled, or partly filled, syringe 2 has a primed patient connection tube (not shown) attached to the nozzle 8 prior to insertion into the housing, and this tube will be occluded to prevent flow by the use of a releasable seal such as a slide clamp or similar device.
• the sealed tube provides a hydraulic lock which enables the insertion of the full syringe. Inserting the syringe will cause the piston 4 to push the plunger 12 away from the nozzle 8, compressing the spring 14 and causing the cord 16 to lose tension.
• a force detector (not shown) on the axle 20 will provide information about the state of the cord 16 (tight or slack) to an electronic controller (not shown), and when the controller detects that the cord is slack the stepper motor 24 is started up to take up the slack, stopping when the cord 16 is fully wound on the axle 2.
• the infusion pump is then ready for use once the patient connection tube has been undamped.
• the worm gear arrangement allows the stepper motor to control the rate at which the cord 16 is allowed to extend from the axle 20, thus allowing the spring 14 to drive the plunger 12, and in turn the syringe piston 4, into the infusate 6 contained in the syringe 2 and therefore into the patient.
• FIG. 4 Another embodiment of the invention is shown, in which the infusate 6 is contained within a collapsible container 46.
• the collapsible container 46 may be an IV bag with flexible walls, as illustrated here, or may have a concertina-like structure.
• the plunger 12 pressurises the infusate 6 by acting directly on a wall of the container 46.
• it is preferred to provide the collapsible container within the receptacle 2 because this helps protect and position it, and define an external shape. It would also be possible to use the collapsible container 46 as the only receptacle for the infusate 6 and in this case the receptacle would be defined by the walls of the collapsible container 46.
• an 'o'-ring 36 disposed around the piston 4 provides a seal; however it will be understood that the sealing function could be provided by the piston itself if formed from a suitable compliant material.
• the piston 4 has a hollow inner threaded portion 38, which receives a syringe handle (not shown) when the syringe 2 is initially filled with liquid. The handle is then removed and the syringe can be inserted into the housing 10.
• the spring 14 acts on a plunger 12 having a central hole in which is fitted a flanged tube 26.
• the cord 16 is disposed through the tube 26 and retained by a stopper 40.
• the plunger 12 has a downwardly and inwardly directed collar 42 which locates on an annular projection 34 on the piston 4.
• the collar 42 is an interference fit for the neck 44 of the piston 4 so that when the two are pushed together the plunger 12 positively locks to the piston 4. This provides an anti- syphon feature which inhibits the piston 4 from travelling away from the plunger 12 if negative pressure is present at the nozzle end.
• the collar 42 has openings in which are received the tips of the arms 32 of the cruciform spring 30.
• the centre of the cruciform spring 30 is lifted relative to the arms 32 so that the spring 30 adopts a retracted configuration in which it does not engage with the wall of the syringe 2.
• the cruciform spring 30 is maintained in this retracted configuration and the piston 4 is free to travel within the syringe 2 when the cord 16 permits the spring 14 to move the piston.
• the cruciform spring 30 is free to adopt a rest configuration in which it is substantially planar and in which the tips of the arms 32 engage with the wall of the syringe 2, as illustrated in Figure 3.
• This engagement provides a braking effect which stops or hinders relative movement between the piston 4 and the nozzle 8.
• the force of the spring 14, via the plunger 12 urges the cruciform spring 30 to change from the retracted configuration to the rest configuration.
• This arrangement provides a self-activating feature for the brake, whereby the greater the spring force urging the plunger to pressurise the liquid, the greater that force urges the brake 30 to be deployed.
• the plunger may be caused to tilt if the cord 16 fails, causing jamming between the plunger or the piston and the syringe wall.
• the electronic control system may be provided with feedback from sensors.
• sensors may measure the cable and/or the position of the plunger or piston.
• the controller Before a syringe is loaded in the housing, the controller may be in an OFF or standby mode, with the force detector on the axle active. When the syringe is inserted in the housing, this is detected by the force detector causing the controller to switch to an ON or active state, or causing the system to 'boot up'. This arrangement helps conserve battery use while providing rapid and failsafe response when a user inserts a syringe.
• the outlet 8 is provided with a screw thread 48, for fitting into a cap 50 which has a complementary internal screw thread 53.
• the cap 50 comprises an inner cap member 52, which carries the screw thread 53, and an outer cap member 51.
• the cap members 51 , 52 are axially slideable relative to one another with a cap spring 54 urging them into an extended configuration.
• a central projecting tube ('Luer') 56 is fluidly connected to a patient connection tube 58 in a manner known per se.
• a spring-biased valve member 66 shown schematically in Fig. 5C. The valve member 66 normally prevents fluid egress from the outlet 8 but permits fluid flow when inwardly displaced.
• the outlet 8 is inserted into the cap 50 and rotated to inter-engage the screw threads 48, 53 (Fig. 5B).
• the cap 50 is fitted to the outlet 8 but fluid cannot pass between them because the valve member 66 is not displaced.
• the housing 10 is provided with a locking sleeve 62 which is slidable and rotatable relative to the housing 10 and which carries a sleeve screw thread 64 which is complementary to a cap screw thread. To permit fluid flow, the locking sl ⁇ eve 62 is slid up the outlet 8 to a point at which the screw threads 60, 64 can inter-engage.

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• Health & Medical Sciences (AREA)
• Vascular Medicine (AREA)
• Engineering & Computer Science (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Hematology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2007
  • 2007-05-18 GB GBGB0709580.5A patent/GB0709580D0/en not_active Ceased
• 2008
  • 2008-05-19 WO PCT/GB2008/001711 patent/WO2008142394A1/en active Application Filing
  • 2008-05-19 EP EP08750642.4A patent/EP2157989B1/de active Active
  • 2008-05-19 US US12/600,124 patent/US9387289B2/en active Active
  • 2008-05-19 JP JP2010507986A patent/JP2010527255A/ja active Pending
  • 2008-05-19 ES ES08750642.4T patent/ES2619651T3/es active Active

Non-Patent Citations (1)

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